The presence of soluble polymeric materials in a sample to be analyzed by chromatography, especially liquid, as opposed to gas, chromatography, often makes it difficult to carry out the liquid chromatography for a number of reasons. Among these reasons, as listed in Elo H. Hansen and Jaromir Ruzicka, FLOW INJECTION ANALYSIS, PART VI. THE DETERMINATION OF PHOSPHATE AND CHLORIDE IN BLOOD SERUM BY DIALYSIS AND SAMPLE DILUTION, ANAL. CHIM. Acta, 87, 353-363, (1976), are:
(1) Interference of proteins and other large molecules with the chromatography.
(2) The tendency of these large molecules to deposit in and foul the conduits, flow cells, etc., of the analyzer.
(3) The signal may be outside the range of the detector.
(4) The amount of sample material available may be less than the minimum amount required for analysis.
A way to reduce the amount of sample required in the use of the Technicon SMA 6/60 by apparatus changes and modified procedure is disclosed in R. W. L. Siebers, SEQUENTIAL DIALYSIS ON THE TECHNICON SMA 6/60 (4+2), N. Z., J. Med. Technol., November 1977. Hansen et al. suggest the other problems may be overcome or mitigated by subjecting the sample to dialysis or sample dilution before injection of the sample material into the capillary column, but their experiments using their equipment, in clinical chromatography, especially of blood serum, were interpreted strongly to favor sample dilution as the better solution to the problems and to avoid dialysis wherever possible.
These prior art proposed systems operate on flow, not on equilibrium as in the present invention; and while it is possible by precise timing to obtain fairly reproducible results with the prior art flow systems, the results are less satisfactory than the results obtainable by the present invention based on equilibrium of ingredients in the dialysis column and out of it as hereinafter defined. Usually the equilibrium system operates intermittently (1) to fill the dialysis column and surrounding annulus, (2) to equilibrate the liquids in the column and annulus (non-flowing), and (3) to remove the equilibrated liquids from the column and annulus. However, dialysis can be carried out in accordance with the invention by continuous flow with significantly better results, particularly a more complete transfer of dialyzable material at a given flow rate, than the prior art systems.